This invention relates to an adhesive system of at least two separate components A and B, the adhesive system comprising    a) as component A an aqueous dispersion of a polymer obtainable by polyaddition or by polymerization of a monomer containing at least one olefinically unsaturated double bond or a mixture of two or more such monomers or an aqueous dispersion of a mixture of two or more such polymers and    b) as component B a dispersion of a drying agent in an oil phase liquid at 23° C., the oil phase containing at least 0.1% by weight of a compound liquid at 23° C. which is soluble in the oil phase and which contains at least one covalent single, double or triple bond between a carbon atom and a hetero atom or a mixture of two or more such compounds,to a process for the production of an adhesive of components A and B and to the use of component B for the production of binders or adhesives, coating compositions and sealants.
Water-based adhesive dispersions are used in many branches of industry for bonding substrates to one another. The use of water-based adhesive dispersions is particularly advantageous when, on the one hand, no solvent-containing vapors are intended to enter the environment during bonding while, on the other hand, the water present in the water-based adhesive dispersion is intended to be able to evaporate without difficulty. However, the use of water-based adhesive dispersions is problematical in particular when either the bonding conditions make it difficult or even impossible for the water to evaporate or the substrate to be bonded is sensitive to water, so that the use of a water-based adhesive dispersion causes damage to the substrate. In addition, water-based adhesives are also not generally suitable for use when the bond is likely to be exposed at least temporarily to an environment of extremely high atmospheric humidity, but is not expected to lose any of its strength under such conditions, or when the bond is exposed even temporarily or permanently to direct contact with water.
Accordingly, water-free adhesives have hitherto been used in the last-mentioned cases, developing their adhesive strength either through the evaporation of a readily volatile solvent or by reaction of two inter-reactive components. Adhesives of the first type are attended by the disadvantage that solvents are emitted into the environment which is not desirable where the adhesives are used indoors in view of the possible health risk posed by the solvents and the noxious odor problem associated with solvent emission. The disadvantage of reactive adhesives of the second type is that they generally contain physiologically hazardous isocyanates, epoxides, polyamines and polyamides. Understandably, users often have reservations about handling such isocyanates, epoxides, polyamines and polyamides.
Accordingly, there was a need for water-based adhesives which could even be used under conditions where evaporation of the water is difficult or largely impossible. There was also a need for water-based adhesives which could even be used in conjunction with water-sensitive substrates. However, such adhesives would be expected to have an adequate pot life, to be able to withstand load stress very soon after the end of their pot life and, in addition, to be suitable for use even indoors, particular emphasis being placed on minimal odor emission. In addition, the adhesives would be expected to show sufficient resistance to water so that they could be used in environments with high air humidity and the strength of the bond would not be affected by at least brief contact with water. Property profiles such as these are required, for example, for adhesives used for bonding laminate or parquet to corresponding substrates in interior rooms.
EP-A 0 782 977 relates to a preparation for waterproofing or vapor-proofing a substrate surface. The document in question describes two components, one an aqueous latex of a natural or synthetic rubber and the other a dispersion of a vulcanizing agent and a hygroscopic compound in an oil phase. Hydrocarbon oils are mentioned as a suitable oil phase, mixtures of hydrocarbon oils, for example a mixture of aromatic and aliphatic compounds, being particularly preferred. It is also stated in the cited document that synthetic liquid plasticizers, such as phthalates or adipates, may be present in the oil phase for adjusting the flow properties. The disadvantage of the system described in the cited document is that both the binder in the aqueous oil phase and the vulcanizing agent can lead to serious odor emissions. In addition, the described suspension of a hygroscopic compound in the hydrocarbon oils mentioned tends to undergo phase separation so that the user has to carry out a dispersion step before using the described preparation. In addition, the described preparations can show unsatisfactory curing behavior for adhesive applications because a relatively long period elapses between the end of the pot life of the preparation and the actual readiness of a surface coating formed from the described preparation to withstand load stress. Finally, nothing is said in the cited document about the use of the compositions described therein as adhesives.
When adhesives are used for bonding floor coverings, effective insulation of the floor covering from the substrate to which it is applied is often required. This insulation relates on the one hand to the transfer of heat between floor and floor covering and on the other hand to the insulating properties of the floor covering, particularly with respect to solid-borne sound. The adhesives known from the prior art are unsatisfactory in this regard because heat insulation and solid-borne sound insulation or both cannot be achieved sufficiently, if at all, using known adhesives.